future.coffee

Simple yet complete implementation of Futures / Promises in CoffeeScript

• Aims to be as simple as possible
• Closely matches the non-deprecated portions of the jQuery 1.9 Deferred API
• Works in a browser environment or as a Node.js module
• Small: 4.4 KB minified, 1 KB gzipped
• No dependencies

Usage

// For Node.js, we must load the module:
// var Future = require('./future');

var computation = new Future();

// Register some completion handlers:

computation.done(function(answer) {
  console.log('The computation has succeeded and the answer was: ' + answer);
});

computation.fail(function(reason) {
  console.log('The computation has failed because: ' + reason);
});

computation.progress(function(percent) {
  console.log('The computation progress is at ' + percent);
});

// Run the computation...

computation.notify('25%');
computation.notify('50%');
computation.notify('75%');

if (Math.random() < 0.5) {
    computation.reject('the universe has imploded');
}
else {
    computation.notify('100%');
    computation.resolve(42);
}

Instead of handing out the Future object to foreign code, you should provide its promise as a substitute. A promise is a restricted proxy of a Future that cannot alter its state with resolve or reject, but can be used to add completion handlers with done, fail, progress, always and then.

....

return computation.promise();

License

MIT.

See also

• jQuery.Deferred
• Q
• avow
• promise.coffee